The overall objective of the Microbiology Core is to provide a set of unique resources for analysis of cystic fibrosis (CF)-related infections. The core has been focused on respiratory tract infections, but a pilot project that received funding from the initial NIDDK Translational Core Center demonstrated Escherichia coli gastrointestinal (GI) dysbiosis in children with CF is associated with inflammation and poor growth. Thus, the focus of the core will be expanded to include GI microbiota. Specific Aims include to: 1) collect, analyze and distribute clinical isolates from the GI tract to investigators seeking to understand the evolution of bacteria subjected to CF selective pressures; 2) continue to collect and distribute lung clinical isolates to investigators studying bacterial pathogenesis, host response and microbial ecology; 3) provide other resources and training for investigators developing new antimicrobial therapies for CF; 4) distribute mutants of Pseudomonas aeruginosa and tools for studies of P. aeruginosa focused on pathogenesis and antimicrobial resistance; 5) provide expert services enabling basic metabolic profiling of bacteria; 6) maintain a unique CF Core Center of Excellence poised to provide technical capabilities to aid researchers in future investigations of CF microbiology. The most used components of the core are large collections of bacterial isolates, both clinical isolates from CF patients and ordered mutant libraries of P. aeruginosa. Other important resources include bacterial metabolic profiling, tools and methods for live fluorescent imagining of bacteria and expertise in novel antibiotic susceptibility testing methods relevant to CF. The Microbiology Core is not only an institutional resource; it has also proven to be an important national and international resource. The Microbiology Core has provided assistance to investigators across the United States and Canada as well as in Europe, Asia and Australia. The microbiology of CF airway infections is a long-standing research strength at Seattle Children's Hospital (SCH) and the University of Washington (UW). Work at these institutions has included both strong basic research activity on key pathogens and significant clinical and translational research leading to the development of novel therapeutics for CF airway infections. SCH has maintained a unique collection of CF clinical isolates from pulmonary infections for decades and will begin archiving GI bacteria for future investigation. The clinical specimen collection has enhanced value because the Microbiology and Clinical Cores work hand-in-hand to make relevant linked clinical information available for archived isolates. The UW- led generation of the first P. aeruginosa genome sequence led to development of a nextGen genomic resource?an ordered library of P. aeruginosa mutants, covering almost every non-essential gene in the originally sequenced strain. These resources and the above services provided by the Microbiology Core enable investigators to make rapid progress in understanding the pathogenesis and metabolic activities of CF- related bacteria and in developing novel therapeutic targets.